With a multidisciplinary approach using methods of clinical opthalamology, electrophysiology, experimental pathology, and biochemistry, we propose to study a hereto unreported inherited degeneration of the retina in the collie dog. 1. Specifically we shall observe behavioral changes of these dogs and correlate the ophthalmoscopic and the ERG changes of their retinas. 2. Detailed light and electron microscopic studies will be done of medial, lateral, dorsal, and ventral quadrants of the central and peripheral retina to study the relationship between rod and cone degeneration, eye pigmentation, and regional differences of the fundus. 3. We shall use radioactive amino acid to study the rate of turnover of the photoreceptor outer segments and the phagocytic activity of the RPE. 4. We shall examine the level of cyclic GMP and activity of phosphodiesterase in the retina during various phases of the retinal dystrophy. 5. We shall examine the effects of light deprivation on one eye and compare with the fellow eye, which has been exposed to cyclic lighting. 6. We shall observe the morphologic changes of the pineal organ and relate these with retinal changes. The ultimate goal of this proposal is to define the clinical, pathologic, physiologic, and biochemical alterations in the dystrophic retina of the collies and to compare these changes with retinal dystrophies in man.